Inverting flap shapes and mechanisms



Dec. 2, 1969 I A. ALVAREZ-CALDERON INVERTING FLAP SHAPES AND MECHANISMS Filed Aug. 21, 1967 445mm A um/2E2 (#4056011 Unitcd States Patent Int. Cl. B64c 3/50 U.S. Cl. 244-42 6 Claims ABSTRACT OF THE DISCLOSURE This invention specifies inverting flaps for wings, with the inverting fiaps having movable nose portions which in high speed flight cooperate to fair the retracted inverting flap to the wing, and in the extended high lift position increase the camber of the flap.

This invention relates to aircraft. More particularly, it relates to flaps for wings. It is a continuation-in-part application of my application Ser. No. 471,274 on inverting flaps filed on July 12, 1965, and now Patent No. 3,371,888.

The characteristics and features of inverting flaps are described in that application, as well as in US. Patent 3,126,173, and will not be repeated here.

One object is to specify flap and slot geometry for singleand double-slotted inverting flaps suitable for very thin wings.

Yet another object of my invention is to specify new and superior slots and flaps shapes for double-slotted flaps on wings.

These and other objectives of my invention will become more evident by inspection of the drawing in which:

FIGURE 1 shows a double-slotted inverting flap arrangement for very thin Wings of the order of 6 percent chord-thickness ratio.

FIGURE 2 shows a single-slotted inverting flap on a very thin airfoil.

FIGURE 3 shows another single-slotted inverting flap on a thin airfoil.

FIGURE 4 shows a double-slotted inverting flap of the type of FIG. 3 but installed on a thick airfoil.

The figures are described hereafter:

FIGURE 1 shows a different double-slotted inverting flap arrangement specially suited for thin wings of the order of 6% thickness-chord ratio.

Specifically, FIG. 1 shows a wing trailing edge 71 supporting a flap pivot axis 72 at which inverting flap in extended position 73 is supported by means of flap bracket 74. Auxiliary flap 75 is pivotally articulated to bracket 74 at connection 76. Its orientation can be defined mechanically by means of a servo on the flap; or by links to the wing. In the drawing, the orientation of auxiliary flap is established by the fact that the resultant force vector 77 acts ahead of pivot 76 tending to produce clockwise rotation which in the extended position of the inverting flap is detained by spacer 78 fixed to the wing. Spacer 78 could as well be fixed to the flaps if preferred by the designer. Further counterclockwise motion of inverting flap from position 9 would obviously retain both slots 79 and 80 through which high-lift airflows 81 and 82 exist. Clockwise motion of inverting flap from position 73 would release contact between auxiliary flap 75 and spacer 78, hence 75 would rotate clockwise under action of force 77 ahead of pivot 76, until lip 83 rests against upper surface of inverting flap. Such position would occur, for example, at 90 flaps. In the closed inverting flap position 84, contact between wing 71 and rounded edge of 75 would additionally establish the position of 75 to act as a smooth fairing between the downwardly facing surface of flap 84 and wing 71.

"ice" It is also possible to pivot auxiliary flap nearer its nose or rounded edge, and let air pressure rotate the flap counterclockwise to open the rear slot, letting wing-flap contact determine the orientation in the retracted position.

Special merits of FIG. 1 is the effective high curvature of the flow bending attained for a very thin wing installation; full use of the wing chord in the flap-extended position is attained; smooth lower surface of wing andv flap when retracted is also attained. There are a minimum number of moving parts, and automatic positioning of auxiliary flap by means of areodynamic forces and fixed spacers is very simple.

FIGURE 2 shows a special arrangement of singleslotted inverting flap 88 in which a pivoted nose 89 is provided to act as a chord-increasing fairing between retracted flap 88 and wing 90; yet the pivoted nose acts as a camber-increasing smooth leading edge radius in position 91 overlapping the extended inverting flap.

Of peculiar merit is the cooperation of pivoted nose 89 to act both as a low-drag fairing to the wing in the retracted position, and as a high-lift camber-increasing fairing to the flap in the extended position. Element 89 can be operated with an electric motor through a gear, or by linkages between flap and wing, or by spring systems.

FIGURE 3 shows an inverting flap in retracted position 94 having a pivoted nose 95 which arts as a landing fairing to wing 96 in the retracted position, or as a camber-increasing element 97 when the inverting fiap is extended. A spacer 98 is used to deflect 97, and a spring 99 plus air pressures straighten out the camber when 98 is not engaged.

FIGURE 4 shows a double-slotted inverting flap arrangement generally similar to that of FIG. 1, except that in FIG. 4 it is installed on the rear portion of an 18% thick airfoil. Specifically, wing 101 supports at axis 103 inverting flap 105 by bracket 107. Of special interest is that auxiliary airfoil 1.09 is pivoted at axis 111 adjacent to rounded edge of 105. Thus when 109 is deflected to relative position 113, which is the high-lift position of 109 when 105 is extended, the effective camber of the combination of flaps 105113 exceeds in depth, by a substantial margin, the flap camber Which could be housed within contour of wing 101. To demonstrate this last feature, position 113 has been shown when the inverting flap is actually retracted. It is evident, therefore, that the auxiliary airfoil arrangement serves to increase the effective camber of the inverting flap when the inverting flap is extended beyond that which could be attained if camber were restricted to the depth available in the trailing edge of the airfoil.

The position of 109 is defined when the inverting flap is retracted, by means of contact with wing at 115; 115 could be a rubber strip. In the extended flap position, 109 is oriented by spacer 117 in a manner similar to FIG. 1.

What is claimed is:

1. A primary airfoil having a trailing edge portion and a trailing edge;

an inverting airfoil mounted on said primary airfoil at a first articulation approximately parallel to said trailing edge, by means of generally chordwise bracket means on said inverting airfoil;

said inverting airfoil being adapted to be moved from a high speed inverted retracted position nested below said trailing edge portion of said primary airfoil, to an extended high lift position trailing said primary airfoil in a camber and chord increasing relationship;

an auxiliary lift element mounted on one of said inverting airfoil and bracket means at a second articulation approximately parallel to said first articulation; said auxiliary lift element being adapted to be positioned with a downwardly facing surface position exposed to the airstream in a drag-reducing disposition approximately parallel with said inverting airfoil when said inverting airfoil is in a retracted position, and said auxiliary airfoil being adapted to be positioned inclined to said drag-reducing disposition to high-lift camber-increasing relationship with respect to said inverting airfoil and adjacent the upstream edge of said inverting airfoil, when said inverting airfoil is in a high-lift extended position, with said auxiliary lift element cooperating to define contracting slot walls between said trailing edge of said primary airfoil and one of said inverting airfoil and auxiliary lift element.

2. The structure of claim 1 further characterized in that said auxiliary element is airfoil-shaped and has a rounded spanwise edge portion and a thin spanwise edge portion, and in that when said auxiliary airfoil is in said high-lift relationship, said rounded edge is spaced from said trailing edge of said primary airfoil to define walls of a first slot therebetween, and said thin edge is spaced away from an upper surface portion of said inverting airfoil to define walls of a second slot therebetween.

3. The structure of claim 1 further characterized in that said auxiliary element is adapted to be inverted with respect to said inverting airfoil from an overlapped disposition when in said high-lift relationship, to a chord-extending position when in said drag-reducing disposition.

4. The structure of claim 1 further characterized in that said auxiliary element is a pivoted nose portion of said inverting airfoil with its high-lift relationship being established by a fixed spacer on one of said trailing edge and said nose portion which deflects said nose portion when said inverting airfoil is in said high-lift position.

5. The structure of claim 2 further characterized in the said airfoil-shaped auxiliary member has a resultant aerodynamic force acting upstream of said second articulation when said inverting airfoil is in said extended position, with said second articulation being located adjacent to an upstream cambered spanwise edge portion of said inverting airfoil.

6. The structure of claim 5 further characterized in that fixed spacer means are provided in one of said trailing edge and said rounded edge, which spacer means defines the slot gap of said first slot.

References Cited UNITED STATES PATENTS 1,893,065 1/1933 Zaparka 24442 2,041,688 5/1936 Barnhart 24442 2,156,403 5/1939 Riviere 244--42 2,379,274 6/ 1945 Boyd 244-42 3,195,836 7/1965 Alvarez-Calderon 24442 FOREIGN PATENTS 113,659 8/ 1941 Australia.

53,254 1/1945 France.

MILTON BUCHLER, Primary Examiner JEFFREY L. FORMAN, Assistant Examiner 

